Removing sql server/ce specific brackets from repository queries as it was causing problems with MySql.

Fixes regression bug from removing brackets from PrimaryKey columns. Columns are now passed and syntax specific brackets are added.
Moving the MySql special case for updating User Id from one to zero.

src/Umbraco.Core/Persistence/SqlSyntax/SqlSyntaxProviderBase.cs

@@ -249,7 +249,9 @@ namespace Umbraco.Core.Persistence.SqlSyntax
 
             string columns = string.IsNullOrEmpty(columnDefinition.PrimaryKeyColumns)
                                  ? GetQuotedColumnName(columnDefinition.Name)
-                                 : columnDefinition.PrimaryKeyColumns;
+                                 : string.Join(", ", columnDefinition.PrimaryKeyColumns
+                                                                     .Split(new[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries)
+                                                                     .Select(GetQuotedColumnName));
 
             string primaryKeyPart = string.Concat("PRIMARY KEY", columnDefinition.IsIndexed ? " CLUSTERED" : " NONCLUSTERED");